title: Dopamine quinone modifies and decreases the abundance of the mitochondrial selenoprotein glutathione peroxidase 4.
abstract: Oxidative stress and mitochondrial dysfunction are known to contribute to the pathogenesis of Parkinson's disease. Dopaminergic neurons may be more sensitive to these stressors because they contain dopamine (DA), a molecule that oxidizes to the electrophilic dopamine quinone (DAQ) which can covalently bind nucleophilic amino acid residues such as cysteine. The identification of proteins that are sensitive to covalent modification and functional alteration by DAQ is of great interest. We have hypothesized that selenoproteins, which contain a highly nucleophilic selenocysteine residue and often play vital roles in the maintenance of neuronal viability, are likely targets for the DAQ. Here we report the findings of our studies on the effect of DA oxidation and DAQ on the mitochondrial antioxidant selenoprotein glutathione peroxidase 4 (GPx4). Purified GPx4 could be covalently modified by DAQ, and the addition of DAQ to rat testes lysate resulted in dose-dependent decreases in GPx4 activity and monomeric protein levels. Exposing intact rat brain mitochondria to DAQ resulted in similar decreases in GPx4 activity and monomeric protein levels as well as detection of multiple forms of DA-conjugated GPx4 protein. Evidence of both GPx4 degradation and polymerization was observed following DAQ exposure. Finally, we observed a dose-dependent loss of mitochondrial GPx4 in differentiated PC12 cells treated with dopamine. Our findings suggest that a decrease in mitochondrial GPx4 monomer and a functional loss of activity may be a contributing factor to the vulnerability of dopaminergic neurons in Parkinson's disease.
authors.affiliation: Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA 15260.
authors.forename: David N
authors.initials: DN
authors.lastname: Hauser
authors.affiliation: Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA 15260.
authors.forename: April A
authors.initials: AA
authors.lastname: Dukes
authors.affiliation: Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA 15260.
authors.forename: Amanda D
authors.initials: AD
authors.lastname: Mortimer
authors.affiliation: Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA 15260; Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260. Electronic address: hastingst@upmc.edu.
authors.forename: Teresa G
authors.initials: TG
authors.lastname: Hastings
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004298:Dopamine / Q000031:analogs & derivatives* / Q000378:metabolism; D059290:Dopaminergic Neurons / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism*; D066298:In Vitro Techniques; D016716:PC12 Cells; D010300:Parkinson Disease / Q000378:metabolism / Q000503:physiopathology; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D051381:Rats
chemical_list: C104705:dopamine quinone; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase; C523860:glutathione peroxidase 4, rat; D004298:Dopamine
keywords: DA; DAQ; DAergic; Dopamine oxidation; GPx4; Mitochondrial dysfunction; PCOOH; PD; Parkinson's disease; SNpc; Selenoproteins; dopamine; dopamine quinone; dopaminergic; phosphatidylcholine hydroperoxide; substantia nigra pars compacta